Fasting is done in many cultures for political, spiritual and health reasons. While some people fast to show their devotion to their deity or to protest an unfair law, there are a large number of people turning to fasting to improve their health. Weight loss is the most commonly cited reason to fast; however, fasting has been shown through a number of studies to have both positive and negative effects on the skin.
If your skin is prone to breakouts or even just the occasional blemish, it is highly possible that while fasting you will experience an episode of acne on or around the third day of your fast. Because you are not putting anything into your body except water, your body is now able to focus on cleansing your system instead of digesting and breaking down food. It is akin to a spring cleaning for your body. While your body is cleansing itself of toxins, some of these will be leaving your body through your skin, creating some blemishes on the surface.
Once your body has adjusted to fasting, usually the fourth or fifth day into a water fast, there is a marked improvement in skin appearance. Staying well-hydrated is very important to achieving this, as your water intake greatly assists your body in quickly flushing out toxins that cause blemishes. Daily vitamins also help your body retain its ability to heal impurities on the skin's surface. If you keep your body well-hydrated, take a daily vitamin, and keep your skin clean and well-moisturized, you can look forward to seeing your skin clear up several days into your fast.
Medical skin conditions such as dermatitis, urticaria and psoriasis have been studied with great attention by medical professionals. In a study conducted by Hamamatsu University School of Medicine in Shizuoka, Japan, it was shown that a fasting diet as treatment for such skin conditions on a monthly basis can improve the skin's condition. Inflammation and frequency of outbreaks, as well as the severity of those outbreaks were diminished when patients were put on a fasting diet. Fasting cannot be sustained as an ongoing form of treatment, but when paired with a sensible vegetarian diet, periods of fasting each month have been shown to significantly improve the condition of the patient's skin. However, it is important to consult with your physician or dermatologist before beginning any new treatment and before discontinuing any current treatment.